I had a bone density test a few months ago and it showed I had osteopenia, too. I'm only 24 and I've never even been on predisone, but I do have a naturally thin build, so that may account for my results partially. My primary doctor told me women's bones continue to become more dense up until around age 30 or so, therefore the test results really have no meaning for me, but two GIs I saw and everything I've read said this is wrong. So, I'm a bit confused, but I am taking two calcium and vit. D supplements a day, in addition to eating plenty of dairy and other foods that contain w/calcium.
As for weight bearing exercises that aren't too strenuous, you could try walking or yoga. There are lots of yoga videos out there if you want to do it from home. Here's a good Web site I found that lists weight-bearing exercises: http://www.nof.org/prevention/exercise.htm
I know how you feel regarding "maybe I shouldn't have asked for the test," but I think it really is better to know now than wait until you may have gotten osteoporosis. At least now there are some things you can do to try to build back up your bones.
I hope your UC gets better soon. I know how hard it is to be able to exercise in any way when you're just trying to stay awake in between trips to the bathroom.
24 years old
Diagnosed with UC March 2007; yet to go into complete remission
Asacol 4 tablets 3x/day
Rowasa (generic) - nightly; Canasa (1,000 mg) in the morning
Nature's Way Primadophilus Reuteri 2/day; Chewable multivitamin; Metamucil; Viactiv